A third generation partnership project (3GPP) mobile system based on a wideband code division multiple access (WCDMA) radio access technology has been widely deployed all over the world. A high-speed downlink packet access (HSDPA), which is a first step in the evolution of the WCDMA, provides the 3GPP with a radio access technology having high competitiveness. However, since radio access technology has been continuously developed in view of requirements and expectations of users and providers, evolution of a new technology in the 3GPP is required to increase competitiveness. There are required reduced cost per bit, increased service availability, flexible use of a frequency band, a simple structure and an open interface, and adequate power consumption of a user equipment.
A wireless communication system is different from a wired communication system in that an user equipment moves. Accordingly, when establishing the wireless communication system, it is required to consider the mobility of the user equipment. The wireless communication system can cope with a situation in which the user equipment moves from one area to another area or cope with varying wireless environments. In addition, a radio link between the network and the user equipment has to be updated based on requests of the user in need. When a radio link configuration needs to be changed, a radio resource control (RRC) layer for managing a radio resource control or lower layer has to rapidly transmit information for configuring a new radio link to the user equipment and rapidly receive information from the user equipment.
When the configuring of a new radio link is delayed, a radio service quality felt by the user may deteriorate. For example, it is assumed that a higher quality cell is found than a cell currently accessed by the user equipment. The user equipment needs to exchange a current cell with a new cell. If a radio link is not reconfigured rapidly enough, the user equipment may lose the connection with the network. When the user equipment initiates to access the new cell with losing the connection, a reconfiguration for the radio link may be lengthen and loss of voice or packet data may occur.
An activation time can be utilized for reconfiguring a radio link. The activation time provides information on when to perform the reconfiguration of the radio link and when to use the new configuration of the radio link. If the network and the user equipment do not use the new configuration concurrently, the call may be lost. For example, assume that in the previous configuration a voice service is provided through a first channel and an internet service is provided through a second channel. In a new configuration, the voice service is provided through the second channel and the internet service is provided through the first channel. If the user equipment uses the new configuration from five past twelve and the system uses the new configuration from six past twelve, the voice service and the internet service do not normally operate for one minute from five past twelve to six past twelve. When the network and the terminal previously know that the new configuration is applied from six past twelve, the aforementioned problem does not occur. Accordingly, the activation time serves to enable the network and the user equipment to synchronize each other before the network and the user equipment use the new configuration.
The problem of the activation time is that the network does not know when the reconfiguration message which includes information of the activation time arrives at the user equipment. In the network, practically, there are considerable messages and data to be transmitted to user equipments. Since radio environments of the user equipments are different from one another, the network does not know the time needed for accurately transmitting the reconfiguration message to specific user equipment. Accordingly, the network determines the activation time based on the worst situation in which the reconfiguration message arrives at the terminal latest.
This causes a delay of the reconfiguration procedure. For example, the new reconfiguration is assumed to be a configuration in which the user equipment enters a sleep mode. At this time, it is assumed that the network determines the activation time to be a time after 3 seconds while transmitting a reconfiguration message for enabling the terminal to enter the sleep mode. The user equipment consumes more power for three seconds than in the case where the terminal enters the sleep mode without delay. This causes waste of power of the user equipment.
It is required a more rapid configuration and/or reconfiguration technique of a radio link.